This invention is in the field of circuits through which it is possible to electrically isolate, monitor and control electrical devices such as switches and motors. The invention pertains more particularly to a high flexibility interface circuit for (a) providing inputs from a first class of electrical devices to a controller and (b) applying output commands from the controller to a second class of electrical devices for the purpose of regulating the actions and functions of such devices in a complex system.
There are many industrial uses of complex systems in which multiple and diverse electrical devices are electrically isolated, monitored and/or controlled by way of relay or relay-like circuits which may operate under the management control of a computer controller. By xe2x80x9ccontrollerxe2x80x9d we refer to a management device such as a programmable digital processor which receives inputs in the form of electrical signals representing at least in part the conditions of a first class of real world electrical devices and which uses those inputs to create commands or outputs in the form of electrical signals which are applied directly or indirectly to a second class of real world electrical devices to determine the functional status thereof. The processor further relates or coordinates inputs to outputs according to a program defining the overall functions or function to be achieved by such devices in a complex system. By xe2x80x9creal worldxe2x80x9d we refer to such devices as switches, solenoids and motors which are associated with work production and/or physical movement or other condition changes in an industrial system as opposed to mere calculations which might occur wholly within a data processor using only logic level signals. The controller may, as stated above, comprise at its heart a general purpose digital microprocessor chip capable of performing data processing and/or management tasks of many kinds. Alternatively, it may comprise a special purpose computer or even a hard wired circuit, the xe2x80x9cprogramxe2x80x9d portion of which is found in the form of hardware or firmware rather than the more traditional applications and operating system software. In general, however, complex systems in industrial applications of all kinds more and more typically include microprocessor chips which are not only flexible in operation and application, but are widely and inexpensively available from various sources and manufacturers such as Intel but are also widely and generally understood and used by engineers and technicians throughout the United States and the world.
An example of an industrial application comprising input type real world devices and output type real world devices operating in a complex system under the control of a data processor is a vehicle laundry wherein such operations as vehicle proximity detection, vehicle length and size assessment, soap spraying, water spraying, brushing, forced air drying, wheel washing and polishing are performed in spaced and overlapping sequences. In such a system, devices which provide condition or function-signaling inputs to a controller-programmer may include, by way of example and not by limitation, vehicle proximity detectors such as limit switches, wand switches and electric eyes, conveyor drive shaft angle encoders, emergency stop switches, keypads, coin boxes and a variety of other devices having contacts which create open and closed circuit conditions. Output or function-causing devices the excitation and operation of which are subject to a remote external control according to the management program found in a controller may include, by way of example and not by limitation, scrubbing brushes, air turbines, hydraulic and pneumatic cylinders, solenoids, pumps, lights, doors, wheel washers, motors and motor starting circuits.
In a more complex but nevertheless typical vehicle laundry it may be desirable to provide a variety of proffered service packages ranging from a simple wet wash to drying, waxing, the application of anti-corrosion agents and wheel washing. The customer may directly select such combinations by way of a credit card reader and keypad or may indirectly make such selections through an attendant who enters an appropriate code from a remote station and provides the customer with a coin or token or code input to simply initiate the operation of the system.
In addition various complex functions are or may be provided in a vehicle laundry such as vehicle proximity detection and vehicle size assessment thereby to schedule the energization and deenergization of various output devices in the system for the purpose of minimizing electrical energy consumption and cost.
In addition it is highly desirable to utilize a general purpose computer as part of the controller of a complex system in order that the general purpose digital computer be available for use in peripheral but related applications such as financial record keeping, maintenance record keeping and scheduling, payroll, employee attendance, machinery usage levels and other data collection and/or coordination functions which are typically associated with the conduct of a retail merchandizing operation. The general purpose computer may, however, be placed at the top of a hierarchy which includes lower order computers which are capable of independent action in the event the master computer experiences a failure or is temporarily unavailable.
Many other industrial applications of a complex nature involving input type electrical devices and output type electrical devices the energization and performance of which are to be coordinated by means of a controller will be apparent to those skilled in the art. Again by way of example and not by limitation, examples of such systems include baggage handling, conveyor systems, automated assembly systems, medical analysis and evaluation systems, access and security systems, construction machinery and other applications characterized by multiple operations on a common workpiece in sequential and coordinated fashion.
One of the problems associated with the construction and operation of complex systems operating under management of a computer-type controller is the typical need to customize electrical circuitry, particularly the interface circuitry which ties the real world electrical devices to the controller either as input devices or output devices. The devices themselves may vary as between simple input devices such as switches, and more complex and power-consuming output devices. In addition, the devices within a single class may vary widely as to excitation voltage and power consumption; e.g., a simple 100 watt filament type light bulb presents an entirely different electrical energization interfacing requirement than an induction motor that might be used to drive a high volume, high velocity air turbine.
Another problem confronting the control circuit designer is the desirability of providing not only for coordinated or integrated automatic control of the various controlled or output devices in a given system but also of providing for independent manual operation of selected devices and, moreover, of providing for overall operation in a coordinated fashion even though the master computer associated with the system may be down as a result of a malfunction or failure. It is doubtless a fact of life that many a complex and elegant computer controlled system has been rendered unproductive by reason of the failure of an inexpensive integrated circuit in a device upon which the overall system is dependent.
It is an object of this invention to provide an interface circuit having relay-like characteristics which is generally applicable to the task of interfacing various types of electrical devices having conductive and non-conductive conditions with a management device of the type described above; i.e., a controller of the type which is programmable to coordinate the functions of various real world electrical devices through the production of output commands and which is further capable of receiving inputs in the form of electrical data signals from other real world electrical devices and which exhibits flexibility in application and operation and in the accommodation of a wide variety of electrical devices of both input and output character.
It is a further object of this invention to provide an interface circuit of the character described above which provides not only for the programmed or automatic control of a wide variety of output type devices, but which also provides for the selective manual energization and operation of individual devices and which, at the same time, provides a logical input to the controller to show that a manual device operation or selection has occurred.
It is a further object of the invention to provide a relay-type interface circuit capable of controlling the application of power to a load device wherein the operating state of the interface circuit and the condition of the associated load device is visually displayed in an easily recognized and non-ambiguous fashion.
It is a further object of the invention to provide an interface circuit of the type and character described above which is utilizable in multiples and on circuit boards in a complex industrial system or device such as a vehicle laundry having multiple input type devices providing data signals as well as multiple output devices which receive commands for programmed operation.
It is a further object of the present invention to provide an interface circuit of the type and character described above in a complex industrial system of the type described above wherein the system operation is conducted under the control of a system having both master and local controller hierarchy such that a loss or failure of the master controller does not render the overall system inoperable but, rather, wherein full programmed and coordinated operation of the system is maintained by virtue of a microprocessors which are locally stationed on circuit boards preferably carrying multiple interface circuits.
It is a further object of the present invention to provide a controller for a complex industrial system consisting of input devices such as switches and output devices such as motors and lights wherein the output devices are called into service in accordance with conditions signalled by the input devices and coordinated by an overall function program. An example given by way of illustration is a vehicle laundry wherein vehicles travel through stations arranged along a conveyor line and are operated upon according to a pre-defined program. Input devices such as limit switches, and electric eyes and conveyor shaft angle encoders signal the presence of a vehicle at each of the stations as well as the operative condition of the devices associated with each station. If a logically-coordinated set of conditions is satisfied; as evidenced by appropriate input signals to the controller; e.g., (a) vehicle present, (b) function-performing device operative, (c) function selected, and (d) no emergency stop signal present, the controller creates an output to a function-causing device turning that device on at and for a prescribed time.
The controller is preferably arranged on a circuit board with multiple input/output device interfaces and equipped with sufficient local memory to carry out the programming needs of a number of output devices as well as at least the input devices associated with those output devices; e.g., a soap dispenser pump and the liquid level detector in the soap reservoir. The combination of the controller and the multiple interfaces is termed a xe2x80x9csmart module.xe2x80x9d
Preferably, each interface circuit is equipped with a remote switch to turn a device on and off under the control of the controller, and a manual switch by which the device may be turned on and off independent of a function-coordinating program. Moreover, each interface circuit is preferably, but not necessarily, equipped with a visual indicator to display its operating status; e.g., AUTO, MANUAL and OFF.
These and other objects and advantages of the invention will be best understood from the reading and understanding of the following specification in which the design and operation of an illustrative interface circuit is given in combination with the disclosure of a vehicle laundry system utilizing multiple interface circuits of the type and character described in detail herein.
Specifically, in the interface circuit illustratively described herein is of the type suitable for use in a combination with various controllers including microprocessor type controller which can produce command signals or outputs for controlling through the interface circuit the condition of a first class of electrical devices and which is capable of receiving via the interface circuit signals in electrical form supplied thereto in accordance with the operating condition of another second class of electrical devices. The interface circuit preferably comprises:
A) a relatively high voltage electrical device energization circuit having a first switch therein for opening and closing the circuit, usually in response to a command signal produced by a controller;
B) a relatively low voltage circuit adapted to receive commands from a controller and an output coupled to the first switch means to place the first switch means in an open circuit condition or a closed circuit condition according to the content of the input command;
C) a second switch means, possibly intended for manual operation, in the electrical device energization circuit also for opening and closing the circuit independently of the first switch means;
D) means interconnecting the second switch means to the input of the command circuit for providing a command equivalent signal thereto when the second switch means is in the closed circuit condition thereby to enable the circuit as if a command had been produced;
E) sensing means, illustratively in the form of a high resistivity shunt circuit connected to an opto-coupler, coupled to the energization circuit and having a first output signal condition when the circuit is closed and a second different output signal condition when the circuit is opened; and
F) a relatively low voltage controller input circuit means coupled to the sensing means to produce an input to the controller according to the signal condition of the sensing means.
In the preferred form hereinafter illustrated, the interface circuit is packaged similar to a relay so as to be mountable along with multiple identical interface circuits on a common printed circuit board, hereinafter called a xe2x80x9csmart module,xe2x80x9d having a local microprocessor which itself is fully operative and fully programmed to carry on the needs and functions of a system, or a substantial portion of the system. The overall function of the local microprocessors may be under the control of a larger and/or remote general purpose master processor which may perform other tasks as well as the management of the complex system described herein. So packaged, it is desirable and preferred to provide in connection with each interface circuit an indicator, preferably in the form of a multi-color LED, for producing a coordinated display representing the states of the command circuit, the controller input circuit and the manual switch. Purely by way of example and not by way of limitation, the LED may be connected to the output circuit to provide a GREEN indication when an input circuit portion of the interface circuit is active, an RED output condition when the output circuit is under the control of the controller and active and an AMBER condition when the manual mode of operation is selected via the manual switch. A fourth condition may be equated to the absence of any color at all from the LED. Of course, multiple single-color LED""s may also be used as well s other types of visual indicators.